Sorting Shapes

Est. Class Sessions: 2

Developing the Lesson

Part 1: Sorting All Shapes

Sort by Number of Sides. If you collected the students' Fill in the Shapes pages from the Student Activity Book at the end of Lesson 9, redistribute one set of pages to each student. Instruct students to cut along the lines on the pages so that they each have a set of shape cards.

Ask students to study the number of sides on each shape. Instruct students to sort the shapes on the cards by the number of sides (three sides, four sides, etc.).

Display the Shape Sort: Sides chart you prepared prior to the lesson. See Figure 1 in Materials Preparation. As other students work, ask some volunteers to attach the shape cards from one display set to the appropriate columns on the class chart. See Figure 6.

After all students have sorted their shapes ask:

Describe the groups you have created. (Possible response: I have groups of 3-sided, 4-sided, 5-sided, and 6-sided shapes.)
Compare your groups to those on the class Shape Sort chart. Did you sort the shapes the same way?
Do you agree with where the shapes are placed on the class Shape Sort chart? Did you place a shape in a different category? Explain.

Take time to discuss any discrepancies with the class.

Then ask:

What do you notice about the corners in each group? (Possible responses: The number of corners matches the number of sides for each shape; some of the shapes have right angles and some don't.)
In each 3-sided shape, are all the sides the same length? What do you notice? (no; Possible responses: Shapes S, U, and BB have sides that are all the same length. Shapes C, V, and AA have sides that are not all the same length.)
Compare the 4-sided shapes. What do you notice? (Possible response: Some of them have parallel sides and some do not.)
Look at the 5-sided shapes. Do you see any right angles? (yes; Shapes R, T, and X all have at least one right angle.)
Compare the 6-sided shapes. What do you notice? (Possible response: Shape Z looks like the yellow hexagon. All of its sides are the same length and its angles are the same. Shapes Q, W, and X have all different side lengths and angles.)
Who would like to add a shape to each category on the chart?

Draw Shapes. Instruct students to use rulers to draw additional examples of the shapes on the Draw Shapes page in the Student Activity Book. Ask a few volunteers to cut out and attach their drawings of 3-sided, 4-sided, 5-sided, and 6-sided shapes to the proper columns on the chart.

Next, introduce and record the following terms on the chart as shown in Figure 6:

triangle—a flat shape with 3 straight sides
quadrilateral—a flat shape with 4 straight sides
pentagon—a flat shape with 5 straight sides
hexagon—a flat shape with 6 straight sides

Point out that the prefixes of each term indicate the number of sides each shape will have.

Ask:

"Sept" means seven. What do you think a septagon would look like? (It is a flat shape with 7 sides.)

Verify that a septagon is a flat shape with 7 straight sides and add the term to the class chart. They are also sometimes called heptagons.

Encourage all students to try drawing a septagon on the Draw Shapes page.

Ask:

Who would like to add a drawing of a 7-sided shape to the class chart? (See Figure 7 for an example.)
"Oct" means eight. What do you think an octagon would look like? (It is a flat shape with 8 sides.)

Verify that an octagon is a flat shape with 8 straight sides and add the term to the chart.

Encourage all students to try drawing an 8-sided shape on the Draw Shapes page.

Who would like to add a drawing of an 8-sided shape to the class chart? (See Figure 8 for an example.)

Sort by Square Corners. Ask students to think about the corners or angles in shapes. Display an orange square pattern block.

Ask:

What does a right angle look like? (Possible response: It means the shape has a square corner.)
How many right angles or square corners does a square pattern block have? (4)
How do you know if an angle is a right angle? How can the square pattern block help you? (Possible response: Right angles look like the capital letter L. If the square pattern block fits perfectly into the angle then it is a right angle.)
Can you find other right angles in the classroom? What are some examples? (Possible responses: the corner of my book; the corner of the table; the corner of the window)

Have students put all of the shape cards back into a pile. Direct students to the Shape Sort pages in the Student Activity Book. Have students use the Square Corners Sorting Mat on the first page to help them place all the shapes that contain right angles into one pile and those that do not into another pile. Encourage students to use an orange square pattern block or the corner of a piece of paper to help them find the square corners.

Display the Shape Sort: Corners chart you prepared prior to the lesson. See Figure 2 in Materials Preparation. As other students work, ask a volunteer to attach the shape cards from one display set to the appropriate columns on the class chart. See Figure 9.

After all students have sorted their cards, ask students to compare their sort to the sort displayed on the class chart and discuss any discrepancies students see. Then ask students to look at the shapes that have right angles.

Ask:

Who would like to use an orange square pattern block to show a right angle in one of the shapes?
Name some shapes that have only right angles. (Shapes F, I, J, K)
Name some shapes that have only one right angle. (Shapes C, V)

Sort by Parallel Sides. Tell students they are now going to think about parallel sides. Display some pattern blocks such as the blue rhombus, yellow hexagon, and red trapezoid.

Ask:

What does it mean when I say "opposite sides?" Give examples. (See Figure 10.)

Explain that what you mean by opposite sides is the sides of a figure that are directly across from each other.

Ask:

Look at the opposite sides on these pattern blocks. Do you see any sides that are parallel? Show us. (See Figure 11.)
Are opposite sides always parallel? Can you show an example? (No, opposite sides are not always parallel; Possible response: Look at the red trapezoid. One set of opposite sides is parallel and one set is not.)

Demonstrate two ways to show parallel lines. First, display a blue rhombus and use a ruler to extend the rhombus' lines. See Figure 12.

Ask:

Will the lines that make the sides of this rhombus ever cross? (no)

Remind students that these are parallel lines. Parallel lines remain the same distance apart over their entire length, like a railroad track. Explain that no matter how far you extend them, they will never meet.

Next, ask students to line up several blue rhombuses. Have them take their fingers and trace the line formed along the top of the shape and the line formed along the bottom of the shape as you demonstrate. See Figure 13.

Ask:

Are these opposite sides parallel? How do you know? (Yes, they are parallel because they stay the same distance apart and they will never meet.)

Direct students to the Parallel Sides Sorting Mat on the Shape Sort pages in the Student Activity Book. Tell students to put all of the shape cards back into a pile. Ask them to think about parallel sides as they use the mat to help them sort, putting the shapes containing parallel sides in one pile and those that do not in another pile.

Display the Shape Sort: Parallel Sides chart you prepared prior to the lesson. See Figure 3 in Materials Preparation. As other students work, ask a volunteer to attach the shape cards from one display set to the appropriate columns on the class chart. See Figure 14.

After all students have sorted their cards, have students compare their sort to the sorted displayed on the class chart and discuss any discrepancies. Then ask volunteers to display shape cards that show shapes containing parallel sides. Have them indicate the parallel sides to the class.

Adventure Book:

Student Activity Book: 697 699 700

Answers